# Sinusoidal Graph - sub intervals

by CrossFit415
Tags: graph, intervals, sinusoidal
 P: 162 1. The problem statement, all variables and given/known data I can find the graphs amp and period. The only problem is finding the sub points or sub intervals. Say... Y = 3 sin (4x) Amp = 3 Period = 2pi/4 = pi/2 But.. don't know how to get the key points of the sub interval. The text book says I have to divide interval [0, pi/2] into four sub intervals Each of length pi/2 divided by 4. Then they got (0,0), (pi/8, 3), (pi/4, 0), (3pi/8, -3), (pi/2, 0) I don't understand how they got these. Thanks 2. Relevant equations 3. The attempt at a solution
 HW Helper P: 3,540 Draw the base graph y=sin(x) with $0\leq x\leq 2\pi$, It has a value of 0 at $x=0,\pi,2\pi$ and a value of 1 and -1 at $x=\pi/2, 3\pi/2$ respectively. Basically, every sine graph of the form $y=Asin(Bx)$ will still have this same shape, but the amplitude (A) and period (B) will be different from the base graph y=sin(x). What you should take away from this is that if the period of sin(x) is $2\pi$, then in between the two ends of the period 0 and $2\pi$ which is $\pi$, it will also be 0, and in between 0 and its half way mark which is $\pi$ we get the value of its amplitude (in this case 1), and between the half way mark and the end, $\pi$ and $2\pi$ we get the negative of its amplitude, -1.
P: 162
 Quote by Mentallic Draw the base graph y=sin(x) with $0\leq x\leq 2\pi$, It has a value of 0 at $x=0,\pi,2\pi$ and a value of 1 and -1 at $x=\pi/2, 3\pi/2$ respectively. Basically, every sine graph of the form $y=Asin(Bx)$ will still have this same shape, but the amplitude (A) and period (B) will be different from the base graph y=sin(x). What you should take away from this is that if the period of sin(x) is $2\pi$, then in between the two ends of the period 0 and $2\pi$ which is $\pi$, it will also be 0, and in between 0 and its half way mark which is $\pi$ we get the value of its amplitude (in this case 1), and between the half way mark and the end, $\pi$ and $2\pi$ we get the negative of its amplitude, -1.
Thanks, I know that but I don't know how to get the points in between the sin graph

I know if period = 2 pi then the middle point would me pi, but what if it has a different period. I don't know what to label on the graph on the middle part.

 HW Helper P: 3,540 Sinusoidal Graph - sub intervals If the period is $2\pi$ then middle is half of that $$\frac{2\pi}{2}=\pi$$. If the period is some number x then the middle is x/2.
 P: 162 Ahhh I see now. Thank you my friend.
 HW Helper P: 3,540 Good luck!

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